Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.
Dabigatran causes the esophageal mucosal injury in approximately 20% of patients. Longitudinally sloughing casts in the distal esophagus are characteristic of dabigatran-induced esophagitis.
Samples from asteroid Ryugu returned by the Hayabusa2 mission contain evidence of extensive alteration by aqueous uids and appear related to the CI chondrites. To understand the sources of the uid and the timing of chemical reactions occurring during the alteration processes, we investigated the oxygen, carbon, and 53 Mn-53 Cr systematics of carbonate and magnetite in two Ryugu particles. We nd that the uid was initially between 0 − 20°C and enriched in 13 C, and 17 O and 18 O, and subsequently evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded. Carbonate ages show that this uid-rock interaction took place within the rst ~ 1.4 million years of solar system history requiring early accretion and preservation of carbonaceous material, either in a planetesimal less than ~ 17 km in diameter or a larger body which was disrupted and reassembled.
Due to their common occurrences in various types of chondrites, igneous rims formed on pre-existing chondrules throughout chondrule-forming regions of the solar nebula. Although the peak temperatures are thought to reach similar values to those achieved during chondrule formation events, the heating duration in chondrule rim formation has not been well defined.We determined the two-dimensional chemical and oxygen isotopic distributions in an igneous rim of a chondrule within the Northwest Africa 3118 CV3oxA chondrite with sub-micrometer resolution using secondary ion mass spectrometry and scanning electron microscopy. The igneous rim experienced aqueous alteration on the CV parent body. The aqueous alteration resulted in precipitation of the secondary FeO-rich olivine (Fa40-49) and slightly disturbed the Fe-Mg distribution in the MgO-rich olivine phenocrysts (Fa11-22) at about a 1 µm scale.However, no oxygen isotopic disturbances were observed at a scale greater than 100 nm. The MgO-rich olivine, a primary phase of igneous rim formation, has d 17 O = -6±3‰ and d 18 O = -1±4 ‰, and some grains contain extreme 16 O-rich areas (d 17 O, d 18 O = ~-30‰) nearly 10 µm across. We detected oxygen isotopic migration of approximately 1 µm at the boundaries of the extreme 16 O-rich areas. Using oxygen self-diffusivity in olivine, the heating time of the igneous rim formation could have continued from several hours to several days at near liquidus temperatures (~2000 K) in the solar nebula suggesting that the rim formed by a similar flash heating event that formed the chondrules.
Kawasaki disease infants younger than 3 months of age appear to be at higher risk for incomplete KD and early-onset CAL prior to the appearance of coronary artery sequelae. We suggest performing an echocardiogram and evaluating NT-proBNP in young infants with fever that has lasted longer than 2 days, regardless of the presence or absence of manifestations associated with KD.
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